1. Field of the Invention
The subject matter of this invention relates generally to puffer circuit interrupters, and relates more particularly to single barrel circuit interrupters with protective nozzles.
2. Description of the Prior Art
It has been known for some time to utilize gaseous environments in circuit breaker apparatus. U.S. Pat. No. 2,757,261 issued to Lingal et al. on July 31, 1956, U.S. Pat. No. 2,798,922 issued to Lingal et al. on July 9, 1957, U.S. Pat. No. 2,809,259 issued to Baker et al. on Oct. 8, 1957 and U.S. Pat. No. 2,733,316 issued to Browne et al. on Jan. 31, 1956 all teach sulfur hexafluoride gas environments for circuit breaker apparatus. The preceding patents teach a relatively static gaseous enviroment in which the insulating and arc extinguishing qualities of sulfur hexafluoride gas are utilized. U.S. Pat. No. 2,824,937 issued to A. P. Strom on Feb. 25, 1958 and U.S. Pat. No. 2,748,226 issued to MacNeill et al. on May 29, 1956 teach the utilization of a blast or flow of sulfur hexafluoride gas for extinguishing an arc. Recently, puffer type compressed gas circuit interrupters have been taught, such as by U.S. Pat. No. 3,852,551 issued Dec. 3, 1974 to C. M. Cleaveland. In the latter case, a piston is mounted internally to an elongated circuit breaker apparatus to operate in conjunction with the operating mechanism for the contacts of the circuit breaker apparatus to provide a puff or jet of gas to the region of the arc during the contact opening operation of the circuit breaker. In the prior art as known, the gas is statically maintained inside the circuit breaker apparatus, or the gas is provided as an external blast of gas from externally stored gas reservoirs or the gas is supplied as part of a two-barrel, piston operated gas puffer. In the latter case, the external barrel provides insulation and support between the terminals of the circuit breaker and the internal barrel provides a separated gas reservoir where gas pressure may be built up during the opening operation of the circuit breaker. A single barrel gas blast circuit interrupter with piston and nozzle arrangement is known but shielding of the arc region and lost motion pressurization therewith is apparently not known. It would be advantageous if there was apparatus in which a single external barrel could be used in conjunction with a piston and nozzle puffer type circuit breaker apparatus where enhanced arc shielding and increased gas pressurization were utilized.